Islamic State, on the offensive, may have just picked up a surface-to-air missile system

The Islamic State’s conquest of Palmyra appears to have netted the group a trove of weaponry, armour, ammunition and equipment that risks fueling a surge of gains by the militants in Syria at a time when attention has been diverted by the end game of the battle for Aleppo.

Palmyra’s fall comes less than a year after Syrian government forces, along with Iranian-backed militias and Russian special operations troops, retook the city from the Islamic State. The group seized the city in 2014, partially destroying a number of its world-renowned archaeological sites.

The recent militant offensive drove Syrian government troops almost completely from the city on Sunday. The Islamic State-linked news agency Amaq later posted images of Syrian and Russian equipment left behind by the retreating troops. One video shows the remains of a Russian forward operating base that had been established after the city was first retaken in March and was used to help with demining efforts there.

Watch: The Russian Pantsir S-1 missile system in action

It is unclear how long the Russian base had been abandoned before the Islamic State’s arrival. Footage taken in what appears to be the facility’s mess hall still shows food bowls on tables, and the scenes are spliced together in a fashion that makes it look as if large stores of ammunition, small arms, heavy machine guns and damaged antiaircraft guns were all left behind. One segment that shows ammunition crates and an antiaircraft gun appears to be within the confines of the Russian base, given the landscape in the background.